Heavy metal status in muscles of dry Trachinocphalus myops fish from Orita-merin market in Ibadan metropolis South-West, Nigeria

This paper determined the levels of chromium (Cr), cadmium (Cd), lead (Pb), copper (Cu) and zinc (Zn) in muscles of dry Trachinocephalus myops from Orita-merin market in Ibadan metropolis south-west of Nigeria. Samples were randomly purchased and were digested in concentrated nitric acid and analyzed by atomic absorption spectrophotometry. Zinc had the highest concentration of 124.9±86.7 mg/kg dry weight of the samples, while cadmium had the lowest concentration of 2.5±1.6 mg/kg dry weight of the samples. The concentration of chromium and copper were 5.6±3.5 mg/kg and 5.2±3.1 mg/kg respectively while lead was observed in only one of the samples with a concentration of 3.7 mg/kg. The obtained result revealed that Cr, Cd, Zn and Pb were above the permissible level set by  the Food and Agricultural Organization (FAO) maximum limit in food which is Pb (2 ppm), Cd (0.5 ppm), Zn(1 ppm), and Cr (0.05 ppm which may be an indication of possible health risk when exposed consistently over a long time to this type of fish. Keywords: Heavy metals, Bioaccumulation, Ecosystem, Pollutant, Exposur

Impact of climate change and anthropogenic activities on renewable coastal resources and biodiversity in Nigeria

Climates related disaster is greatly human induced warming, leading to substantial fluctuations in earth temperature which is currently a global issue of environmental concern. Human proximity and pressure in and around the coastal region has threatened flora, fauna and micro-organic resources of economic importance in most developing nations. Two-third of the word populations lives in or around the coast and 16 of the 23 world mega cities are currently in the world coastal belt. Transitively, the coastal environment, which harbors the highest percentage of biodiversity, is significantly important for economic activities and leisure. Nigeria's climate may witness increases in temperature, rainfall, storms, and sea levels throughout the twenty-first century and improper management of these desiccations can result into degradation in some parts of the country. Apart from climate change, coastal environment is subject to various anthropogenic impacts, often associated with high population, industrial and agricultural activities. Both disasters have led to heat stress, sea level rise, and erosion, salinization of the soil, evapo- transpiration, desertification and others. The overall resultant effects are feasible on environmental indicators including renewable coastal resources. It is therefore recommended among others that thinking globally and acting locally on environmental issues could save our coastal nation

Electrochemical Aptasensor for Endocrine Disrupting 17β-Estradiol Based on a Poly(3,4-ethylenedioxylthiopene)-Gold Nanocomposite Platform

A simple and highly sensitive electrochemical DNA aptasensor with high affinity for endocrine disrupting 17β-estradiol, was developed. Poly(3,4-ethylenedioxylthiophene) (PEDOT) doped with gold nanoparticles (AuNPs) was electrochemically synthesized and employed for the immobilization of biotinylated aptamer towards the detection of the target. The diffusion coefficient of the nanocomposite was 6.50 × 10−7 cm2 s−1, which showed that the nanocomposite was highly conducting. Electrochemical impedance investigation also revealed the catalytic properties of the nanocomposite with an exchange current value of 2.16 × 10−4 A, compared to 2.14 × 10−5 A obtained for the bare electrode. Streptavidin was covalently attached to the platform using carbodiimide chemistry and the aptamer immobilized via streptavidin—biotin interaction. The electrochemical signal generated from the aptamer–target molecule interaction was monitored electrochemically using cyclic voltammetry and square wave voltammetry in the presence of [Fe(CN)6]−3/−4 as a redox probe. The signal observed shows a current decrease due to interference of the bound 17β-estradiol. The current drop was proportional to the concentration of 17β-estradiol. The PEDOT/AuNP platform exhibited high electroactivity, with increased peak current. The platform was found suitable for the immobilization of the DNAaptamer. The aptasensor was able to distinguish 17β-estradiol from structurally similar endocrine disrupting chemicals denoting its specificity to 17β-estradiol. The detectable concentration range of the 17β-estradiol was 0.1 nM–100 nM, with a detection limit of 0.02 nM

Electrochemical Aptasensor for Endocrine Disrupting 17β-Estradiol Based on a Poly(3,4-ethylenedioxylthiopene)-Gold Nanocomposite Platform

A simple and highly sensitive electrochemical DNA aptasensor with high affinity for endocrine disrupting 17β-estradiol, was developed. Poly(3,4-ethylenedioxylthiophene) (PEDOT) doped with gold nanoparticles (AuNPs) was electrochemically synthesized and employed for the immobilization of biotinylated aptamer towards the detection of the target. The diffusion coefficient of the nanocomposite was 6.50 × 10−7 cm2 s−1, which showed that the nanocomposite was highly conducting. Electrochemical impedance investigation also revealed the catalytic properties of the nanocomposite with an exchange current value of 2.16 × 10−4 A, compared to 2.14 × 10−5 A obtained for the bare electrode. Streptavidin was covalently attached to the platform using carbodiimide chemistry and the aptamer immobilized via streptavidin—biotin interaction. The electrochemical signal generated from the aptamer–target molecule interaction was monitored electrochemically using cyclic voltammetry and square wave voltammetry in the presence of [Fe(CN)6]−3/−4 as a redox probe. The signal observed shows a current decrease due to interference of the bound 17β-estradiol. The current drop was proportional to the concentration of 17β-estradiol. The PEDOT/AuNP platform exhibited high electroactivity, with increased peak current. The platform was found suitable for the immobilization of the DNAaptamer. The aptasensor was able to distinguish 17β-estradiol from structurally similar endocrine disrupting chemicals denoting its specificity to 17β-estradiol. The detectable concentration range of the 17β-estradiol was 0.1 nM–100 nM, with a detection limit of 0.02 nM

Heavy metals in some termite species and their nests in Ojo, Lagos, Nigeria

Termites feed on decaying organic matter including plant parts and wood, concentrating heavy metals in the process. The main campus of Lagos State University was surveyed for termite species and their heavy metal contents. Nests including mounds, wooden structures and discarded wood products were observed for termite activities and the insect samples collected for identification and subsequent metal analyses. Composite samples of selected termite species and the soil or wood dust around them were respectively digested and analyzed for the presence of Iron (Fe), Potassium (K), Sodium (Na). Zinc (Zn) Cadmium (Cd), Copper (Cu), Chromium (Cr), Lead (Pb), Nickel (Ni) and Cobalt (Co) using Atomic Absorption Spectrophotometer (AAS). The results showed that Macrotermes bellicosus (Isoptera: Macrotermitinae), Reticulitermes flavipes (Isoptera: Rhinotermitidae) and Kalotermes flavicollis (Isoptera: Kalotermitidae) occurred on the main campus of Lagos State University in Ojo, Lagos. Heavy metal analyses of termite castes showed that M. bellicosus worker had Ni, Fe, Cd, Co, Pb, Na and K with Fe having the highest concentration of 24.6 mgL-1 while Co had the least (0.03mgL-1). The reproductive caste had the highest concentration (4.68 mgL-1). The Soldier of M. bellicosus showed the presence of all metals detected in its worker caste excluding Cu & Ni with Fe having the highest concentration (5.12mg/L). The Soldier and Worker castes of Kalotermes similarly showed the presence of the same metals as M. bellicosus soldier. Analyses of data by Kyplot showed high correlation between heavy metal concentrations in study termite species relative to their nest materials.Keywords: Heavy metals, Termites, Worker, Soldier, Winged Reproductive, Kyplot analysi